24 A MANUAL OF MOSSES 



fibrillose; branch-leaves usually truncate and toothed or fringed, 



rarely acute. e. 



b. Chlorophyllose cells of leaves exposed either dorsally or ven- 



trally, or both. c. 



b. Chlorophyllose cells, as seen in cross-section, centrally placed 

 and enclosed by the hyaline cells both dorsally and ven- 

 trally. 4. S. medium. 



c. Lateral walls of the chlorophyllose cells with fibrillose thicken- 

 ings on the surfaces facing into the hyaline cells. 



1. S. imbricatum. 

 c. Lateral walls of the chlorophyllose cells smooth. 



d. 

 d. Chlorophyllose cells very broadly triangular or triangularly 

 trapezoidal with the broader face ventral. 



2. S. affine. 



d. Chlorophyllose cells narrowly triangular or trapezoidal, not 

 over one-half as wide as long, usually less. 



3. 5. latifolium. 



e. Chlorophyllose cells triangular or trapezoidal in cross-section with 



one or both faces free. f. 



e. Chlorophyllose cells elliptical, or more or less barrel-shaped or 

 rectangular, but not triangular nor trapezoidal. 



m. 

 f. Face of chlorophyltese cells free on the ventral surface; hya- 

 line cells dorsally strongly convex, the interior cell-walls ad- 

 joining the chlorophyllose cells smooth. 



g. {Actitifolia) . 

 f. Face of chlorophyllose cells dorsally free; hyaline cells ven- 

 trally strongly convex, the interior walls smooth or papillose. 



K. 



g. Stem-leaves erose- or lacerate-fimbriate at the broadly rounded 

 apex, non-fibrillose. 10. S- Umbriatum. 



g. Stem-leaves not fimbriate but truncate or toothed at the apex, 

 non-fibrillose. h. 



h. Stem-leaves Ungulate; plants usually reddish. 



11. S. mornstorfii. 



h. Stem-leaves more or less equilaterally triangular or triangu- 

 lar-Ungulate, i. 

 i. Branch-leaves S-seriate, when dry not lustrous. 



12. 5. quinquefarium. 

 i. Branch-leaves not S-seriate, when di'y sometimes lustrous. 



j. Stem-leaves usually non-fibrillose and non-porose; branch- 

 leaves usually lustrous when dry. 13. 5. subnitens. 

 j. Stem-leaves usually fibrillose and porose; branch-leaves not 

 glossy when dry. 14. S. capillifolium. 



k. Hyaline cells of median dorsal leaf-surface of branch-leaves with 

 about 5 very large pores, pores smaller towards the leaf-apex; 

 chlorophyllose cells with the exterior walls strongly thickened. 



1. iSquarrosa) . 

 k. Hyaline cells with pores on median dorsal leaf-surface none or 

 very few; chlorophyllose cells with exterior walls not strongly 

 thickened. s. iCuspidata). 



1. Branch-leaves mostly squarrose in apical half of leaf. 



6. S. squarrosum. 

 1. Branch-leaves slightly or not at all squarrose. 



7. 5. teres. 



ra. Hyaline cells of stem-leaves non-fibrillose; chlorophyllose cells 

 of branch-leaves enclosed on both surfaces, the lumen sub-central, 



